Dynamic measurement of motion of a moving object, for example, a vibrating object, is conventionally done using camera based systems that capture successive images of the moving object at successive intervals of time, whereby a motion characteristic is determined based on the position of the object in successively captured image frames. Other known techniques for measurement of vibration motion include the use of strain gages and laser Doppler based methods. However, such techniques are typically suitable for measuring two-dimensional motion and hence cannot be conveniently used for measuring three-dimensional motion such as spatial modes of vibration, which are important for damage and impact analysis of machine parts and civil structures.
In particular, camera based systems capture displacement of various points on a surface of a moving object over time. However, these systems are limited by the frame rate of the camera used, which is a function of the time interval between the capture of two successive image frames. The cost of cameras increases as the frame rates increases, thereby inducing a practical limit on the frame rate. This poses a difficulty in capturing high speed motion by such systems as they have a maximum and minimum limitation of speed for a moving object.